This invention relates to trailers, and more particularly to trailers having a plurality of wheels to be towed by a vehicle, wherein all of the trailer wheels are simultaneously steered to achieve accurate tracking.
Over the years there has been a great deal of effort to develop trailers which accurately track behind a towing vehicle. In many industrial applications, it is not uncommon to pull a train of trailers behind a towing vehicle to distribute parts throughout a large plant. It is quite important for the trailers to accurately track behind the towing vehicle, particularly when the train of trailers is long, in order to prevent the trailers from colliding with obstacles. In order to achieve accurate trailer tracking, a number of trailer manufacturers have gone to a four wheel steered trailer. The wheels are steered in response to tongue rotation. Typically, the system of steering linkages interconnect the wheels and the tongue, and in some instances a combination of steering linkages and cable arrangement is employed to interconnect the wheels and the tongue, as shown in U.S. Pat. Nos. 3,820,811, 3,529,848 and 2,673,091.
The mechanical joints and a tie rod system necessarily have some mechanical clearance which allows wheel wobble, which invariably increases with wear. Previous attempts to develop an all-cable steering system to eliminate the mechanical linkages is shown in U.S. Pat. No. 3,077,354, which utilizes a very complicated cable/chain arrangement having a complex slack adjustment system.